STUDY OF THE EFFECTS OF TOTAL MODULATION TRANSFER FUNCTION CHANGES ON OBSERVER PERFORMANCE USING CLINICAL MAMMOGRAMS

The main goal of this study was to relate physical changes in image quality measured by Modulation Transfer Function (MTF) to diagnostic accuracy.^ One Hundred and Fifty Kodak Min-R screen/film combination conventional craniocaudal mammograms obtained with the Pfizer Microfocus Mammographic system were selected from the files of the Department of Radiology, at M.D. Anderson Hospital and Tumor Institute.^ The mammograms included 88 cases with a variety of benign diagnosis and 62 cases with a variety of malignant biopsy diagnosis. The average age of the patient population was 55 years old. 70 cases presented calcifications with 30 cases having calcifications smaller than 0.5mm. 46 cases presented irregular bordered masses larger than 1 cm. 30 cases presented smooth bordered masses with 20 larger than 1 cm.^ Four separated copies of the original images were made each having a different change in the MTF using a defocusing technique whereby copies of the original were obtained by light exposure through different thicknesses (spacing) of transparent film base.^ The mammograms were randomized, and evaluated by three experienced mammographers for the degree of visibility of various anatomical breast structures and pathological lesions (masses and calicifications), subjective image quality, and mammographic interpretation.^ 3,000 separate evaluations were anayzed by several statistical techniques including Receiver Operating Characteristic curve analysis, McNemar test for differences between proportions and the Landis et al. method of agreement weighted kappa for ordinal categorical data.^ Results from the statistical analysis show: (1) There were no statistical significant differences in the diagnostic accuracy of the observers when diagnosing from mammograms with the same MTF. (2) There were no statistically significant differences in diagnostic accuracy for each observer when diagnosing from mammograms with the different MTF's used in the study. (3) There statistical significant differences in detail visibility between the copies and the originals. Detail visibility was better in the originals. (4) Feature interpretations were not significantly different between the originals and the copies. (5) Perception of image quality did not affect image interpretation.^ Continuation and improvement of this research ca be accomplished by: using a case population more sensitive to MTF changes, i.e., asymptomatic women with minimum breast cancer, more observers (including less experienced radiologists and experienced technologists) must collaborate in the study, and using a minimum of 200 benign and 200 malignant cases.^

A qualitative assessment of the impact of Texas policy changes on nutrition in child care centers in Travis County, Texas

Background. Over half of children in the United States under age five spend 32 hours a week in child care, facilities, where they consume approximately 33-50% of their food intake. ^ Objectives. The aim of this research was to identify the effects of state nutrition policies on provision of food in child care centers. ^ Subjects. Eleven directors or their designee from ten randomly selected licensed child care centers in Travis County, Texas were interviewed. Centers included both nonprofit and for-profit centers, with enrollments ranging from 19 to 82. ^ Methods. Centers were selected using a web-based list of licensed child care providers in the Austin area. One-on-one interviews were conducted in person with center directors using a standard set of questions developed from previous pilot work. Interview items included demographic data, questions about state policies regarding provision of foods in centers, effects of policies on child care center budgets and foods offered, and changes in the provision of food. All interviews were audiotaped and transcribed, and themes were identified using standard qualitative techniques. ^ Results. Four of the centers provided both meals and snacks, four provided snacks only, and two did not provide any food. Directors of centers that provided food were more likely to report adherence to the Minimum Standards than directors of centers that did not. In general, center directors reported that the regulations were loosely enforced. In contrast, center directors were more concerned about a local city-county regulation that required food permits and new standards for kitchens. Most of these local regulations were cost prohibitive and, as a result, centers had changed the types of foods provided, which included providing less fresh produce and more prepackaged items. Although implementation of local regulations had reduced provision of fruits and vegetables to children, no adjustments were reported for allocation of resources, tuition costs or care of the children. ^ Conclusions. Qualitative data from a small sample of child care directors indicate that the implementation and accountability of food- and nutrition-related guidelines for centers is sporadic, uncoordinated, and can have unforeseen effects on the provision of food. A quantitative survey and dietary assessment methods should be conducted to verify these findings in a larger and more representative sample.^

Impact of fee schedules and approved doctor's list on physician availability in the Texas Workers' Compensation Program

The purpose of this study was to examine and describe the changes in physician provider workforce, before and after two regulatory changes were implemented by the Texas Workers' Compensation Commission (TWCC) in August and September of 2003: Fee schedules and the Approved Doctor's List (ADL). The number and type of physicians who participated in the program after the changes went into effect were measured and compared to projections based on natural attrition. In addition, interviews with key stakeholders were conducted regarding the program changes. ^ Collectively, this evidence suggests that physician response followed the same patterns as shown in previous research. The number of physicians who continued to participate and bill the Texas workers' compensation program decreased significantly as a result of the regulatory changes. The consequences of these changes on access and quality of care need to be documented with empirical research. The availability of physicians in the workforce is linked to access to care. The type and location of physicians who remained in the system also have impact on quality and access to care. ^